diff --git a/eclair/common_config.ecl b/eclair/common_config.ecl
index c8e1b8f..e2e7737 100644
--- a/eclair/common_config.ecl
+++ b/eclair/common_config.ecl
@@ -3,14 +3,7 @@
 -eval_file=public_APIs.ecl
 -public_files+=api:public
 
--doc_begin="Treat LIBC as external, as they have many peculiar declarations leading to spurious warnings."
--file_tag+={external, "^include/lib/libc/.*$"}
--file_tag+={external, "^lib/libc/.*$"}
--doc_end
-
--file_tag+={external, "^lib/compiler-rt/.*$"}
--file_tag+={external, "^include/lib/libfdt/.*$"}
--file_tag+={external, "^lib/libfdt/.*$"}
+-eval_file=external_sources.ecl
 
 -doc="Build version file is autogenerated and piped directly to compiler, captured by ECLAIR as /dev/pipe/XXX, changing from build to build, leading to spurious diffs."
 #-file_tag+={external, "^_ROOT/dev/pipe/.*$"}
diff --git a/eclair/external_sources.ecl b/eclair/external_sources.ecl
new file mode 100644
index 0000000..535a2c0
--- /dev/null
+++ b/eclair/external_sources.ecl
@@ -0,0 +1,18 @@
+#
+# Copyright (c) 202-2023, Arm Limited. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+# External aka 3rd-party sources included in a project.
+# These are intended to be filtered from MISRA reports (as we don't have
+# control over them, can't easily fix issues in them, and generally that's
+# normally out of scope of the project).
+
+-doc_begin="Treat LIBC as external, as they have many peculiar declarations leading to spurious warnings."
+-file_tag+={external, "^include/lib/libc/.*$"}
+-file_tag+={external, "^lib/libc/.*$"}
+-doc_end
+
+-file_tag+={external, "^lib/compiler-rt/.*$"}
+-file_tag+={external, "^include/lib/libfdt/.*$"}
+-file_tag+={external, "^lib/libfdt/.*$"}